Ignition system for internal-combustion engines.



H. R. VAN DEVENTER.

IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES.

APPLICATION FILED 050.24. I914.

1,142,920, Patented June 15, 1915.

fninrnn s'rarns PATENT. OFFICE.

IGNITION SYSTEM FOR INTERNAL-COMBUSTION ENGINES.

.spgq flyet not Letters tent Patented June 15-, 1915.

Application filed December 24, 1914. Serial No. 878,934.

To all whom it may co'ncernr Be it known that I, HARRY RANDOLPH VAN DEVENTER, a' citizen of 'the United States, residing at Sumter, in the' county of Sumter and State of South Carolina, have invented certain new and useful Improvements i'n Ignition Systems for Intermil-Combustion Engines, of which the following is a specification, reference being had to the accompanying drawing.

My invention relates to ignition systems for internal combustion engines and has for its object the provision of an ignition sys-' tem employing an electric generator, and in which the current at the sparking points in the engine cylinder is periodically reversed, thereby preventing the troubles occasioned by a uni-directional spark.

There are other objects which will hereinafter appear;

A more complete-understanding'of my invention will'be hadby reference to the accompanying drawings in which Figure'l is a-diagram illustrating sparking points as affected by unidirectional cufrent, Fig. 2,' a diagram showing the efiect of reversing thecurrent at the pomts, Fig. 3, a diagram showing the relation between the engine cycles and the cycles of the current source such as a magneto, and'Fig. 4 a diagram showing the collector ring of a magneto to illustrate one of the advantages of my invention. I

Like figures of reference denote the sam parts wherever they are shown.

I do not showan ignition generator mounted on an engine, as such arrangements are well-known, and to carry out my inven tion, the only difference .Would' be the employment of driving gears or other driving means, whereby the magneto is drivenat a certain relative speed as hereinafter described. Such an arrangement of gear wheels in itself presents nothing new, so it is not illustrated here. i

In Fig. 1 is shown a pair of spark points or electrodes of'either the make and break, or jump spark type. These are positioned in the engine cylinderyand when in circuit with a suitable source of current of a uni directional natnre, one of the electrodes becomes pointed as indicated in Fig. 1 at 1" while-a crater is formed in the other as shown at 2. This action'is'similar to that taking place'between the carbons of an ordinary direct current are lamp, and is partic'ularly noticeable with make and break igniters. To overcome this trouble it has heretofore been customary to periodically reverse the polarity of the source of current, which not only requiresattention, but also a suitable switch for changing the connections, all of which is troublesome and liable to be forgotten. Furthermore this could not be done frequently enough to be of material service. Usually with stationary engines the current would be reversed only once a day, or, when a reversing commutating device is used, complication results.

In Fig. 2 is shown the condition of a pair of contact points in a circuit where the current How is reversed sufliciently often to prevent the condition shown in Fig. 1. The ideal condition is when each alternate impulse is of opposite polarity, the reason for this being that the'particles of metal carried from electrode 2 to electrode 1 by a current flowing in a "given'direction, is by the next impulse transferred from 1 back to 2, which maintains the adjacent surfaces of the electrodes smooth, thereby preventing wasting of the metal, and maintaining a uniform gap, as indicated in Fig. 2.

There are other advantages gained by my invention. For instance practically all magnetos of the alternating current typeare made with'some form of collector ring having a brush bearing thereon. It is obvious that when the current is delivered across the gap of the spark plug or igniter in a unidirectional manner that the collector brush a is always on the same point 6 on the collector ring 0, whereas when the current is of alternate polarity, two points 6 and d of the ring are used thereby reducing the wear on the brush and ring due to sparking'at one point. In other words the wear due to the ring a pitting at one point is halved.

My invention contemplates the use of a magneto of the alternating current direct driven type. Heretofore it has'been common practice to gear such magnetos directly with the'engine crank shaft gear or the half time gear, or in some other suitablemanner, so that the revolutions of the magneto armature'or'rotor shaft bear a certain fixed relation to the revolutions of the engine crank shaft. Heretofore the commonly used driving'speeds have been crank shaft or engine speed,'o'r an even multiple 'the'reoflsometlmes plus one half crank shaft speed. For instance, A representing the speed of the engine crank shaft in a single cylinder four cycle engine, the magneto would be drlven at A, 2A or A plus one-halfA, or 2A plus one-half A, etc. At none of these speeds would the spark be reversed at the spark points at alternate explosions, as is evidenced by the diagram Fig. 3 in which 3 represents the ordinary shuttle wound armature of a magneto running at engine speed. The line 4 represents the piston cycle of a single cylinder 4 cycle engine, and also the cycle of the magneto armature traveling at crank shaft speed. It will be observed that the plus spark is always produced with the piston in the firing position, that is to say the flow of current across the spark points is uni-directional. I have found it is possible to obtain a spark reversal at alternate explosions by gearing the magneto armature to revolve in certain speed relations to the crank shaft speed, which may best be expressed as follows:

Azspeed of the crank shaft or any multiple thereof.

Bzone-fourth crank shaft speed. Xzrequired speed of magneto.

Then

A plus B=X AB=X As an example, take an engine having a crank shaft speed of 200 R. P. M. It is desion, then A plus B=250,

the driving speed of the magneto, or 13g times engine speed. On some slow moving engines, it is desired to gear the magneto up so as to increase the current output, in which case, assuming the crank shaft speed to be 100, then 2A plus 18:225

or 23} times engine speed. In some cases on high speed engines, it is desired to reduce the speed of the magneto, in which case-A equaling 500, B equaling 125,

or 2; engine speed. There are other conditions of service wherein it is desired to obtain certain relative speeds on account of the spark range of the magneto. Such conditions are readily met by the wide choice of driving speeds it is possible to employ without sacrificing the reversed current feature herein described.

By reference to Fig. 3, it will be clear that this method of drive accomplishes the spark reversal at alternate explosions. 5 is the armature of a magneto driven at 1% times engine speed. The various positions it assumes in relation to the piston cycle is easily seen, and it will be observed how the direction of the flow of current is reversed at each alternate firing stroke, being first plus, then minus, as shown, then plus, and so on. 6 represents the cycle of the magneto armature, and corresponds to line 4, the piston cycle. Note the magneto armature is always one-fourth revolution ahead of the crank From the foregoing it will be observed that my invention consists broadly of driving the magneto armature at such a speed in relation to the engine crank shaft that both peaks of the alternating current are used, alternately, in some definite relation to the crank shaft revolutions. And while I show the magneto driven at a speed to produce current reversal at alternate firing strokes of the engine, I do not confine myself to this arrangement as other gear ratios may be used whereby the reversal takes place at other related periods, thereby approximating to a more or less degree the ideal method of alternate reversal herein described. And it Will be obvious to those skilled in the art that the method herein disclosed is applicable to high or low tension magnetos, and any of the ignitersused therewith. And while I have described my invention as used in connection with a single cylinder 4 cycle engine, it is obvious that the same principle may be employed in connection with 2 cycle engines and also that by means of a dis tributer or other well known arrangement, it

may be employed with multicylinder engines. All such applications and modifications, and the methods of calculating the same are within the scope of this invention as they are obvious to those skilled in the art.

Having thus described my invention, I claim:

1. In combination with an internal combustion engine, an alternating current gen erator, an igniter, and means for driving said generator from said engine whereby both polarities of the alternating current are alternately utilized at the igniter in timed relation to the firing moment of said engine.

2. In combination with an internal combustion engine, an alternating current generator, an igniter, and means for driving said generator from said engine whereby currents of opposite polarity are generated at predetermined alternate intervals of time in timed relation to the firing moment of said engine.

3. In combination with an internal com bustion engine, an alternating current generator, an igniter, and means for driving said generator from said engine whereby the speed of said generator is the speed of the engine crank shaft or a multiple thereof, plus one-fourth the crank shaft speed, for the purpose set forth.

4:. In combination with an internal combustion engine, an alternating current generator, an igniteryand means for driving said generator from said engine whereby the speed of said generator is the speed of the engine crank shaft or a multiple thereof, less one-fourth crank shaft speed, for the purpose set forth.

5. In combination with an. internal oombustion engine, an alternating current generator having an H type shuttle-wound armature, and driving means for said generator whereby currents of alternate opposite polarities are generated in predetermined cyclic relation to the engine revolution.

6. In an internal combustion engine, a

ma eto ignition system having the magneto gea gd with the crank shaft at a speed ratio of three-quarters to one.

7. In an internal combustion elnigine, a ma eto i ition system havin t e ma netg geare with the crank shaf at a spe d ratio of one and one-fourth to one. I

8. In an internal combustion engine, a magneto ignition system having the magneto geare with the crank shaft at a speed ratio of one and three-quarters to one.

9. In an internal combustion engine, a

magneto ignition system having the magneto geared with the crank shaft at a speed ratio of twoand one-quarter to one.

10. In an internal combustion engine, a magneto ignition system having the magneto geare with the crank shaft at a speed ratio of two and three-fourths to one.

11. In an internal combustion engine, a magneto i 'tion system having the magneto geare with the crank shaft at a speed ratio of three and one-fourth to one.

12. In an internal combustion engine, a magneto ignition system having the magneto geare with the crank shaft at a speed ratio of three and three-fourths to one.

13. The method of igniting the charge in an internal combustion engine which consists in generating a single phase current wave, timing the peaks of said current wave to the sparking moment of the engine, and utilizing said peaks alternately over predetermined reoccurring time intervals in relation to the sparking moment of the en e.

In testimony whereof I hereunto a my signature in t e presence of two witnesses.

HARRY RANDOLPH VAN DEVENTEB. Witnesses:

EDNA IsLnR, E. H. Emma. 

